Keyboard control for sliders

backends/x/window.go

@@ -238,6 +238,9 @@ func (window *Window) reallocateCanvas () {
 	newHeight := window.metrics.height
 	larger    := newWidth > previousWidth || newHeight > previousHeight
 	smaller   := newWidth < previousWidth / 2 || newHeight < previousHeight / 2
+
+	allocStep := 128
+	
 	if larger || smaller {
 		if window.xCanvas != nil {
 			window.xCanvas.Destroy()
@@ -246,8 +249,8 @@ func (window *Window) reallocateCanvas () {
 			window.backend.connection,
 			image.Rect (
 				0, 0,
-				(newWidth  / 64) * 64 + 64,
-				(newHeight / 64) * 64 + 64))
+				(newWidth  / allocStep + 1) * allocStep,
+				(newHeight / allocStep + 1) * allocStep))
 		window.xCanvas.CreatePixmap()
 	}
 	
@@ -291,16 +294,23 @@ func (window *Window) childDrawCallback (region canvas.Canvas) {
 func (window *Window) paste (canvas canvas.Canvas) (updatedRegion image.Rectangle) {
 	data, stride := canvas.Buffer()
 	bounds := canvas.Bounds().Intersect(window.xCanvas.Bounds())
+
+	dstStride := window.xCanvas.Stride
+	dstData   := window.xCanvas.Pix
+	
 	// debug.PrintStack()
-	for x := bounds.Min.X; x < bounds.Max.X; x ++ {
 	for y := bounds.Min.Y; y < bounds.Max.Y; y ++ {
-		rgba := data[x + y * stride]
-		index := x * 4 + y * window.xCanvas.Stride
-		window.xCanvas.Pix[index + 0] = rgba.B
-		window.xCanvas.Pix[index + 1] = rgba.G
-		window.xCanvas.Pix[index + 2] = rgba.R
-		window.xCanvas.Pix[index + 3] = rgba.A
-	}}
+		srcYComponent := y * stride
+		dstYComponent := y * dstStride
+		for x := bounds.Min.X; x < bounds.Max.X; x ++ {
+			rgba := data[srcYComponent + x]
+			index := dstYComponent + x * 4
+			dstData[index + 0] = rgba.B
+			dstData[index + 1] = rgba.G
+			dstData[index + 2] = rgba.R
+			dstData[index + 3] = rgba.A
+		}
+	}
 
 	return bounds
 }

elements/basic/slider.go

@@ -83,7 +83,24 @@ func (element *Slider) HandleMouseMove (x, y int) {
 func (element *Slider) HandleMouseScroll (x, y int, deltaX, deltaY float64) { }
 
 func (element *Slider) HandleKeyDown (key input.Key, modifiers input.Modifiers) {
-	// TODO: handle left and right arrows
+	switch key {
+	case input.KeyUp:
+		element.changeValue(0.1)
+	case input.KeyDown:
+		element.changeValue(-0.1)
+	case input.KeyRight:
+		if element.vertical {
+			element.changeValue(-0.1)
+		} else {
+			element.changeValue(0.1)
+		}
+	case input.KeyLeft:
+		if element.vertical {
+			element.changeValue(0.1)
+		} else {
+			element.changeValue(-0.1)
+		}
+	}
 }
 
 func (element *Slider) HandleKeyUp (key input.Key, modifiers input.Modifiers) { }
@@ -135,6 +152,20 @@ func (element *Slider) SetConfig (new config.Config) {
 	element.redo()
 }
 
+func (element *Slider) changeValue (delta float64) {
+	element.value += delta
+	if element.value < 0 {
+		element.value = 0
+	}
+	if element.value > 1 {
+		element.value = 1
+	}
+	if element.onRelease != nil {
+		element.onRelease()
+	}
+	element.redo()
+}
+
 func (element *Slider) valueFor (x, y int) (value float64) {
 	if element.vertical {
 		value =